I want to allow a caller to press 0 at a boolean field, but I don't see a way to distinguish between pressing 0 and saying "no" because the output from the built-in boolean grammar includes zero.

I'd rather not re-implement a version of the boolean grammar myself to work around this problem. Is there a way I might accept a dtmf "0" at a boolean prompt but still distinguish between pressing "0" vs saying "no"?

The data we get back is either “1” or “0": pressing 1 or saying yes returns a “1”, pressing 2 or saying no returns a “0"